Material for organic electroluminescent device and organic electroluminescent device using the same

ABSTRACT

A material for an organic electroluminescent device and an organic electroluminescent device including the same, the material including a monoamine compound represented by the following Formula 1:

CROSS-REFERENCE TO RELATED APPLICATION

Japanese Patent Application No. 2014-195147, filed on Sep. 25, 2014, inthe Japanese Patent Office, and entitled: “Material for OrganicElectroluminescent Device and Organic Electroluminescent Device Usingthe Same,” is incorporated by reference herein in its entirety.

BACKGROUND

1. Field

Embodiments relate to a material for an organic electroluminescentdevice and an organic electroluminescent device using the same.

2. Description of the Related Art

Recently, the development of an organic electroluminescent display isbeing actively conducted. In addition, the development of an organicelectroluminescent device, which is a self-luminescent device used inthe organic electroluminescent display, is also being activelyconducted.

As the organic electroluminescent device, a structure may include, e.g.,an anode, a hole transport layer disposed on the anode, an emissionlayer disposed on the hole transport layer, an electron transport layerdisposed on the emission layer and a cathode disposed on the electrontransport layer.

SUMMARY

Embodiments are directed to a material for an organic electroluminescentdevice and an organic electroluminescent device using the same.

The embodiments may be realized by providing a material for an organicelectroluminescent device, the material including a monoamine compoundrepresented by the following Formula 1:

wherein, in Formula 1, R₁ and R₂ are each independently a hydrogen atom,a halogen atom, an alkyl group having 1 to 15 carbon atoms, asubstituted or unsubstituted aryl group having 6 to 30 ring carbonatoms, or a substituted or unsubstituted heteroaryl group having 1 to 30ring carbon atoms, and Ar₁ is a moiety represented by the followingFormula 2,

—(Ar₂)₁—(Ar₃)_(m)—Ar₄   [Formula 2]

wherein, in Formula 2, Ar₂, Ar₃, and Ar₄ are each independently asubstituted or unsubstituted aryl group having 6 to 50 ring carbonatoms, and l+m is an integer from 0 to 2.

Ar₁ may include three combined or condensed substituted or unsubstitutedphenyl groups.

Ar₁ may include a substituted or unsubstituted phenanthrenyl group.

Ar₁ may include a substituted or unsubstituted p-terphenyl group.

Ar₁ may include a substituted or unsubstituted naphthalenylphenyl group.

All dibenzofuranyl groups that are directly bonded with a nitrogen atomof the monoamine may be bound to the nitrogen atom at a 3 position ofthe dibenzofuranyl group.

The compound represented by Formula 1 may include one of the followingcompounds:

The embodiments may be realized by providing an organicelectroluminescent device including a material for an organicelectroluminescent device, wherein the material for an organicelectroluminescent device includes a monoamine compound represented bythe following Formula 1:

wherein, in Formula 1, R₁ and R₂ are each independently a hydrogen atom,a halogen atom, an alkyl group having 1 to 15 carbon atoms, asubstituted or unsubstituted aryl group having 6 to 30 ring carbonatoms, or a substituted or unsubstituted heteroaryl group having 1 to 30ring carbon atoms, and Ar₁ is represented by the following Formula 2,

—(Ar₂)₁—(Ar₃)_(m)—Ar₄   [Formula 2]

wherein, in Formula 2, Ar₂, Ar₃, and Ar₄ are each independently asubstituted or unsubstituted aryl group having 6 to 50 ring carbonatoms, and l+m is an integer from 0 to 2.

The material for an organic electroluminescent device may be included ina hole transport layer.

The compound represented by Formula 1 may include one of the followingcompounds:

BRIEF DESCRIPTION OF THE DRAWINGS

Features will be apparent to those of skill in the art by describing indetail exemplary embodiments with reference to the attached drawings inwhich:

FIG. 1 illustrates a schematic cross-sectional view of an organicelectroluminescent device according to an embodiment; and

FIG. 2 illustrates an NMR spectrum of Compound C according to anembodiment.

DETAILED DESCRIPTION

Example embodiments will now be described more fully hereinafter withreference to the accompanying drawings; however, they may be embodied indifferent forms and should not be construed as limited to theembodiments set forth herein. Rather, these embodiments are provided sothat this disclosure will be thorough and complete, and will fullyconvey exemplary implementations to those skilled in the art.

In the drawing figures, the dimensions of layers and regions may beexaggerated for clarity of illustration. It will also be understood thatwhen a layer or element is referred to as being “on” another layer orelement, it can be directly on the other element, or interveningelements may also be present. In addition, it will also be understoodthat when an element is referred to as being “between” two elements, itcan be the only element between the two elements, or one or moreintervening elements may also be present. Like reference numerals referto like elements throughout.

<1. Configuration of Material for Organic Electroluminescent Device>

Materials for an organic electroluminescent device according to anembodiment may help improve the emission life of an organicelectroluminescent device. For example, when using the material for anorganic electroluminescent device according to an embodiment as a holetransport material, the emission life of the organic electroluminescentdevice may be improved. Here, the configuration of the material for anorganic electroluminescent device according to an embodiment will beexplained. The material for an organic electroluminescent deviceaccording to an embodiment of may include, e.g., a monoamine compoundrepresented by the following Formula 1.

In Formula 1, Ar₁ may be or include a moiety represented by thefollowing Formula 2.

—(Ar₂)₁—(Ar₃)_(m)—Ar₄   [Formula 2]

In Formula 2, Ar₂, Ar₃ and Ar₄ may each independently be or include,e.g., a substituted or unsubstituted aryl group having 6 to 50 ringcarbon atoms. l and m are integers, and l+m may be an integer of 0 to 2.

In an implementation, Ar₁ may be obtained by combining or condensingthree substituted or unsubstituted phenyl groups. For example, Ar₁ mayinclude three substituted or unsubstituted phenyl groups connected by asingle bond (as in a terphenyl group), may include three fusedsubstituted or unsubstituted phenyl groups (as in an anthracenyl group),or a combination thereof (as in a phenyl group singly bonded to anaphthyl group). For example, Ar₁ may include a phenyl group, a biphenylgroup, a terphenyl group, a naphthyl group, an anthryl group, aphenanthryl group, a naphthalenylphenyl group, a fluorenyl group, anindenyl group, a pyrenyl group, a fluoranthenyl group, a triphenylnenylgroup, or the like. In an implementation, Ar₁ may include the phenylgroup, the biphenyl group, the terphenyl group (e.g., a p-terphenylgroup), the naphthyl group, the phenanthryl group, thenaphthalenylphenyl group, and/or the triphenylenyl group.

The aryl group of Ar₁ may be substituted. In an implementation, thesubstituents may include an alkyl group (e.g., a methyl group, an ethylgroup, etc.), an alkenyl group (e.g., a vinyl group, an allyl group,etc.), a halogen atom (e.g., a fluorine atom, a chlorine atom, etc.), asilyl group (e.g., a trimethylsilyl group), a cyano group, an alkoxygroup (e.g., a methoxy group, a butoxy group, an octoxy group), a nitrogroup, a hydroxyl group, a thiol group, or the like, e.g., other thanthe aryl group. In an implementation, the substituent may include afunctional group other than the vinyl group, the indolyl group, and thetriphenylenyl group, in consideration of thermal stability. In animplementation, the substituents may further be substituted with thesame types of substituents.

In an implementation, in a case in which Ar₁ includes a phenanthrenylgroup, the glass transition temperature may be unusually high for themolecular weight of the monoamine compound. Thus, the thermal stabilityof the molecule thereof may be increased, and a layer quality may beimproved. Therefore, in the case that Ar₁ includes the phenanthrenylgroup, the emission life of the organic electroluminescent device may belargely improved. In an implementation, a phenanthrenyl group may forman aromatic ring with other atoms (e.g., a heteroatom such as a nitrogenatom).

In an implementation, in a case in which Ar₁ does not include thephenanthrenyl group, the emission life may still be increased. Forexample, in the case that the emission life may be increased even whenAr₁ is a substituent obtained by combining or condensing three phenylgroups (a terphenyl group, a naphthalenylphenyl group, etc.). In3-substituted dibenzofuran which is the essential structure of themonoamine compound, m position of a heteroatom of oxygen may be combinedwith or bound to nitrogen. Thus, even if Ar₁ does not include thephenanthrenyl group, the emission life may still be increased.

In Formula 1, R₁ and R₂ may each independently be or include, e.g., ahydrogen atom, a halogen atom (e.g., a fluorine atom, a chlorine atom,etc.), an alkyl group having 1 to 15 carbon atoms, a substituted orunsubstituted aryl group having 6 to 30 ring carbon atoms, or asubstituted or unsubstituted heteroaryl group having 1 to 30 ring carbonatoms.

The alkyl group having 1 to 15 carbon atoms may be, e.g., a linear type(e.g., a methyl group, an ethyl group, a propyl group, a butyl group, anoctyl group, a decyl group, a pentadecyl group, etc.) or a branched type(e.g., a t-butyl group, etc.).

The aryl group having 6 to 30 ring carbon atoms may include an arylgroup having 6 to 30 ring carbon atoms among the above-described arylgroups. The heteroaryl group having 1 to 30 ring carbon atoms mayinclude a heteroaryl group having 4 to 30 ring carbon atoms among theabove-described heteroaryl groups. In an implementation, the heteroarylgroup may include, e.g., a tetrazolyl group, an imidazolyl group, apyrazolyl group, an oxazolyl group, an isooxazolyl group, a thiazolylgroup, an isothiazolyl group, or the like. The substituent of the arylgroup and the heteroaryl group may be the same as the above-describedsubstituent of the aryl group and the heteroaryl group of Ar₁.

In an implementation, as shown in Formula 1, at least one of thedibenzofuranyl groups making a direct linkage with the central nitrogenatom of the monoamine may be combined with or bound to the nitrogen atomat position 3 of the dibenzofuranyl group. In an implementation, all(e.g., both) dibenzofuranyl groups making a direct linkage with thenitrogen atom may be combined with or bound to the nitrogen atom atposition 3. In this case, the emission life of the organicelectroluminescent device may be further improved.

The material for an organic electroluminescent device according to anembodiment may be included in at least one of a hole transport layer andan emission layer, among layers constituting an organicelectroluminescent device. In an implementation, the material for anorganic electroluminescent device may be included in the hole transportlayer.

The organic electroluminescent device using or including the materialfor an organic electroluminescent device having the above-mentionedconfiguration may exhibit improved emission life, as described in thefollowing embodiments. In an implementation, the compound represented byFormula 1 may include one of the following compounds.

<2. Organic Electroluminescent Device Using Material for OrganicElectroluminescent Device>

Referring to FIG. 1, the organic electroluminescent device including orusing the material for an organic electroluminescent device according toan embodiment will be described in brief. FIG. 1 illustrates a schematiccross-sectional view of an organic electroluminescent device accordingto an embodiment.

As shown in FIG. 1, the organic electroluminescent device 100 accordingto an embodiment may include, e.g., a substrate 110, a first electrode120 disposed on the substrate 110, a hole injection layer 130 disposedon the first electrode 120, a hole transport layer 140 disposed on thehole injection layer 130, an emission layer 150 disposed on the holetransport layer 140, an electron transport layer 160 disposed on theemission layer 150, an electron injection layer 170 disposed on theelectron transport layer 160, and a second electrode 180 disposed on theelectron injection layer 170.

In an implementation, the material for an organic electroluminescentdevice according to an embodiment may be included in at least one of thehole transport layer and the emission layer. In an implementation, thematerial for an organic electroluminescent device may be included inboth layers. In an implementation, the material for an organicelectroluminescent device may be included in the hole transport layer140.

Each of the organic thin layers disposed between the first electrode 120and the second electrode 180 of the organic electroluminescent devicemay be formed by various suitable methods, e.g., an evaporation methodor the like.

The substrate 110 may be a substrate suitable for use in an organicelectroluminescent device. For example, the substrate 110 may be a glasssubstrate, a semiconductor substrate, or a transparent plasticsubstrate.

The first electrode 120 may be e.g., an anode and may be formed by anevaporation method, a sputtering method, etc. on the substrate 110. Forexample, the first electrode 120 may be formed as a transmission typeelectrode using a metal, an alloy, a conductive compound, etc. havinghigh work function. The first electrode 120 may be formed using e.g.,transparent and highly conductive indium tin oxide (ITO), indium zincoxide (IZO), tin oxide (SnO₂), zinc oxide (ZnO), etc. In animplementation, the anode 120 may be formed as a reflection typeelectrode using magnesium (Mg), aluminum (Al), etc.

On the first electrode 120, the hole injection layer 130 may be formed.The hole injection layer 130 may be a layer equipped with the functionof the easy injection of holes from the first electrode 120 and may beformed, e.g., on the first electrode 120 to a thickness of from about 10nm to about 150 nm. The hole injection layer 130 may be formed using asuitable material. The hole injection layer 130 may include, e.g.,triphenylamine-containing poly ether ketone (TPAPEK),4-isopropyl-4′-methyldiphenyliodoniumtetrakis(pentaflorophenyl)borate(PPBI),N,N′-diphenyl-N,N′-bis-[4-(phenyl-m-tolyl-amino)-phenyl]-phenyl-4,4′-diamine(DNTPD), a phthalocyanine compound such as copper phthalocyanine,4,4′,4″-tris(3-methyl phenylphenylamino)triphenylamine (m-MTDATA),N,N′-di(1-naphthyl)-N,N′-diphenylbenzidine (NPB),4,4′,4″-tris{N,N-diphenylamino}triphenylamine (TDATA),4,4′,4″-tris(N,N-2-naphthylphenylamino)triphenylamine (2-NATA),polyaniline/dodecylbenzenesulfonic acid (Pani/DBSA),poly(3,4-ethylenedioxythiophene)/poly(4-styrenesulfonate) (PEDOT/PSS),polyaniline/camphorsulfonic acid (Pani/CSA),polyaniline/poly(4-styrenesulfonate (PANI/PSS), or the like.

On the hole injection layer 130, the hole transport layer 140 may beformed. The hole transport layer 140 may be formed by stacking aplurality of layers. The hole transport layer 140 may be a layerincluding a hole transport material equipped with hole transportingfunction and may be formed, e.g., on the hole injection layer 130 to athickness from about 10 nm to about 150 nm. The hole transport layer 140may be formed using the material for an organic electroluminescentdevice according to an embodiment. In an implementation, in the case inwhich the material for an organic electroluminescent device according toan embodiment is used as the host material of the emission layer 150,the hole transport layer 140 may be formed using a suitable holetransport material. The hole transport material may include, e.g.,1,1-bis[(di-4-tolylamino)phenyl]cyclohexane (TAPC), a carbazolederivative such as N-phenyl carbazole, polyvinyl carbazole, etc.N,N′-bis(3-methylphenyl)-N,N′-diphenyl-[1,1-biphenyl]-4,4′-diamine(TPD), 4,4′,4″-tris(N-carbazolyl)triphenylamine (TCTA),N,N′-di(1-naphthyl)-N,N′-diphenylbenzidine (NPB), or the like.

On the hole transport layer 140, the emission layer 150 may be formed.The emission layer 150 may be formed to, e.g., a thickness from about 10nm to about 60 nm. The material of the emission layer 150 may include asuitable luminescent material, e.g., may be selected from fluoranthenederivatives, pyrene derivatives, arylacetylene derivatives, fluorenederivatives, perylene derivatives, chrysene derivatives, or the like. Inan implementation, the pyrene derivatives, the perylene derivatives, andthe anthracene derivatives may be used. For example, the material of theemission layer 150 may include, e.g., an anthracene derivativerepresented by the following Formula 12.

In Formula 12, each Ar₉ may independently be or include, e.g., ahydrogen atom, a deuterium atom, a substituted or unsubstituted alkylgroup having 1 to 50 carbon atoms, a substituted or unsubstitutedcycloalkyl group having 3 to 50 ring carbon atoms, a substituted orunsubstituted alkoxy group having 1 to 50 carbon atoms, a substituted orunsubstituted aralkyl group having 7 to 50 carbon atoms, a substitutedor unsubstituted aryloxy group having 6 to 50 ring carbon atoms, asubstituted or unsubstituted arylthio group having 6 to 50 ring carbonatoms, a substituted or unsubstituted alkoxycarbonyl group having 2 to50 carbon atoms, a substituted or unsubstituted aryl group having 6 to50 ring carbon atoms, a heteroaryl group having 5 to 50 ring carbonatoms, a substituted or unsubstituted silyl group, a carboxyl group, ahalogen atom, a cyano group, a nitro group, or a hydroxyl group. n maybe an integer of 1 to 10.

In an implementation, each Ar₉ may include, e.g., a phenyl group, abiphenyl group, a terphenyl group, a naphthyl group, a phenylnaphthylgroup, a naphthylphenyl group, a phenanthryl group, a fluorenyl group,an indenyl group, a pyrenyl group, an acetonaphthenyl group, afluoranthenyl group, a triphenylenyl group, a pyridyl group, a furanylgroup, a pyranyl group, a thienyl group, a quinolyl group, anisoquinolyl group, a benzofuranyl group, a benzothienyl group, anindolyl group, a carbazolyl group, a benzooxazolyl group, abenzothiazolyl group, a quinoxalyl group, a pyrazolyl group, adibenzofuranyl group, a dibenzothienyl group, or the like. In animplementation, each Ar₉ may include, e.g., the phenyl group, thebiphenyl group, the terphenyl group, the fluorenyl group, the carbazolylgroup, the dibenzofuranyl group, or the like.

In an implementation, the compound represented by Formula 12 may be oneof the following Compounds a-1 to a-12.

The emission layer 150 may include a dopant such as styryl derivatives(e.g., 1,4-bis[2-(3-N-ethylcarbazolyl)vinyl]benzene (BCzVB),4-(di-p-tolylamino)-4′-[(di-p-tolylamino)styryl]stilbene (DPAVB),N-(4-((E)-2-(6-((E)-4-(diphenylamino)styryl)naphthalene-2-yl)vinyl)phenyl)-N-phenylbenzeneamine(N-BDAVBi)), perylene and the derivatives thereof (e.g.,2,5,8,11-tetra-t-butylperylene (TBPe)), pyrene and the derivativesthereof (e.g., 1.1-dipyrene, 1,4-dipyrenylbenzene,1,4-bis(N,N-diphenylamino)pyrene), or the like.

On the emission layer 150, an electron transport layer 160 including amaterial having tris(8-hydroxyquinolinato)aluminum (Alq₃) or anitrogen-containing aromatic ring (e.g., a material including a pyridinering such as 1,3,5-tri[(3-pyridyl)-phen-3-yl]benzene, a materialincluding a triazine ring such as2,4,6-tris(3′-(pyridin-3-yl)biphenyl-3-yl)-1,3,5-triazine, a materialincluding an imidazole derivative such as2-(4-(N-phenylbenzoimidazolyl-1-ylphenyl)-9,10-dinaphthylanthracene) maybe formed. The electron transport layer 160 may be a layer including anelectron transport material for an electron transport function and maybe formed on the emission layer 150 to a thickness from about 15 nm toabout 50 nm. On the electron transport layer 160, the electron injectionlayer 170 may be formed using a material including e.g., lithiumfluoride, lithium-8-quinolinato (Liq), or the like. The electroninjection layer 170 may be a layer for facilitating injection ofelectrons from the second electrode 180 and may be formed to a thicknessfrom about 0.3 nm to about 9 nm.

In addition, on the electron injection layer 170, the second electrode180 may be formed. The second electrode 180 may be, e.g., a cathode. Forexample, the second electrode 180 may be formed as a reflection typeelectrode using a metal, an alloy, a conductive compound, etc. havinglow work function. The second electrode 180 may be formed using e.g.,lithium (Li), magnesium (Mg), aluminum (Al), aluminum-lithium (Al—Li),calcium (Ca), magnesium-indium (Mg—In), magnesium-silver (Mf—Ag), etc.In addition, the second electrode 180 may be formed as a transmissiontype electrode using ITO, IZO, etc. Each of the above-mentioned layersmay be formed by selecting an appropriate layer forming method such as avacuum evaporation method, a sputtering method, various coating methods,etc. according to materials used.

The organic electroluminescent device 100 including the material for anorganic electroluminescent device according to an embodiment may haveimproved emission life.

In an implementation, the organic electroluminescent device 100according to embodiments may be formed using the structures of variousother suitable organic electroluminescent devices. For example, theorganic electroluminescent device 100 may not be provided with one ormore layers of the hole injection layer 130, the electron transportlayer 160, and the electron injection layer 170. In an implementation,each layer of the organic electroluminescent device 100 may be formed asa single layer or a multilayer.

In an implementation, the organic electroluminescent device 100 may beprovided with a hole blocking layer between the electron transport layer160 and the emission layer 150 to help prevent the diffusion of tripletexcitons or holes to the electron transport layer 160. In animplementation, the hole blocking layer may be formed using e.g.,oxadiazole derivatives, triazole derivatives or phenanthrolinederivatives.

EXAMPLES

Hereinafter, the organic electroluminescent device according to anembodiment of the present disclosure will be explained in particularreferring to examples and comparative examples. However, The followingExamples and Comparative Examples are only illustrations of the presentdisclosure, and the scope of the present disclosure is not limitedthereto.

Synthetic Example 1 Synthesis of Compound C

Compound C was synthesized according to the following synthetic scheme.

(Synthesis of Compound B)

Under an argon atmosphere, 15.00 g of Compound A, 0.85 g of cuprousoxide, 20 ml of an aqueous ammonia solution, and 70 ml of NMP were addedto a 500 ml three necked flask, followed by heating at about 110° C. forabout 25 hours. After air cooling, water was added, an organic layer wasseparated, and solvents were distilled. The crude product thus obtainedwas separated using silica gel column chromatography (hexane/ethylacetate) to produce 7.4 g of Compound B as a white solid (Yield 66%).The molecular weight of Compound B thus obtained was measured usingFAB-MS, and a value of 193 (C₁₄H₁₁N) was obtained.

(Synthesis of Compound C)

Under an argon atmosphere, 1.00 g of Compound B, 2.81 g of3-bromo-dibenzofuran, 0.27 g of bis(dibenzylideneacetone)palladium(0),0.088 g of tri-tert-butylphosphine and 3.98 g of sodium tert-butoxidewere added to a 500 ml three necked flask, followed by heating andrefluxing in 200 ml of a toluene solvent for about 7 hours. After aircooling, water was added to the reactant, an organic layer wasseparated, and solvents were distilled. The crude product thus obtainedwas separated using silica gel column chromatography (toluene/hexane) toproduce 1.90 g of Compound C as a white solid (Yield 70%). The molecularweight of Compound C thus obtained was measured using FAB-MS, and avalue of 525 (C₃₈H₂₃NO₂) was obtained. In addition, ¹H NMR (CDCl₃, 300MHz) of Compound C was measured, and the chemical shift values shown inFIG. 2 were obtained. Thus, the synthesis of Compound C was secured. Inaddition, the glass transition temperature of Compound C was measuredusing a differential scanning calorimetry, DSC 7020 of Hitachi HightechCo., and a value of Tg: 120° C. was obtained.

Synthetic Example 2 Synthesis of Compound E

Compound E was synthesized according to the following synthetic scheme.

(Synthesis of Compound D)

Under an argon atmosphere, 1.00 g of Compound B, 1.41 g of3-bromo-dibenzofuran, 0.27 g of bis(dibenzylideneacetone)palladium(0),0.088 g of tri-tert-butylphosphine and 3.98 g of sodium tert-butoxidewere added to a 500 ml three necked flask, followed by heating andrefluxing in 200 ml of a toluene solvent for about 7 hours. After aircooling, water was added to the reactant, an organic layer wasseparated, and solvents were distilled. The crude product thus obtainedwas separated using silica gel column chromatography (toluene andhexane) to produce 1.10 g of Compound D as a white solid (Yield 59%).The molecular weight of Compound D thus obtained was measured usingFAB-MS, and a value of 359 (C₂₆H₁₇NO) was obtained.

(Synthesis of Compound E)

Under an argon atmosphere, 1.00 g of Compound D, 0.75 g of3-bromo-dibenzofuran, 0.13 g of bis(dibenzylideneacetone)palladium(0),0.044 g of tri-tert-butylphosphine and 1.99 g of sodium tert-butoxidewere added to a 500 ml three necked flask, followed by heating andrefluxing in 200 ml of a toluene solvent for about 7 hours. After aircooling, water was added to the reactant, an organic layer wasseparated, and solvents were distilled. The crude product thus obtainedwas separated using silica gel column chromatography (toluene andhexane) to produce 1.10 g of Compound E as a white solid (Yield 75%).The molecular weight of Compound E thus obtained was measured usingFAB-MS, and a value of 525 (C₃₈H₂₃NO₂) was obtained. In addition, ¹H NMR(CDCl₃, 300 MHz) of Compound E was measured, and the chemical shiftvalues expected from the structure of Compound E were obtained. Thus,the synthesis of Compound E was secured. In addition, the glasstransition temperature of Compound E was measured using a differentialscanning calorimetry, DSC 7020 of Hitachi Hightech Co., and a value ofTg: 115° C. was obtained.

Synthetic Example 3 Synthesis of Compound G

Compound G was synthesized according to the following synthetic scheme.

Under an argon atmosphere, 1.34 g of Compound F, 2.96 g of3-bromo-dibenzofuran, 0.27 g of bis(dibenzylideneacetone)palladium(0),0.088 g of tri-tert-butylphosphine and 3.98 g of sodium tert-butoxidewere added to a 500 ml three necked flask, followed by heating andrefluxing in 200 ml of a toluene solvent for about 7 hours. After aircooling, water was added to the reactant, an organic layer wasseparated, and solvents were distilled. The crude product thus obtainedwas separated using silica gel column chromatography (toluene andhexane) to produce 2.20 g of Compound G as a white solid (Yield 70%).The molecular weight of Compound G thus obtained was measured usingFAB-MS, and a value of 577 (C₄₂H₂₇NO₂) was obtained. In addition, ¹H NMR(CDCl₃, 300 MHz) of Compound G was measured, and the chemical shiftvalues expected from the structure of Compound G were obtained. Thus,the synthesis of Compound G was secured. In addition, the glasstransition temperature of Compound G was measured using a differentialscanning calorimetry, DSC 7020 of Hitachi Hightech Co., and a value ofTg: 100° C. was obtained.

Synthetic Example 4 Synthesis of Compound I

Compound I was synthesized according to the following synthetic scheme.

Under an argon atmosphere, 1.13 g of Compound H, 2.81 g of3-bromo-dibenzofuran, 0.27 g of bis(dibenzylideneacetone)palladium(0),0.088 g of tri-tert-butylphosphine and 3.98 g of sodium tert-butoxidewere added to a 500 ml three necked flask, followed by heating andrefluxing in 200 ml of a toluene solvent for about 7 hours. After aircooling, water was added to the reactant, an organic layer wasseparated, and solvents were distilled. The crude product thus obtainedwas separated using silica gel column chromatography (toluene/hexane) toproduce 1.85 g of Compound I as a white solid (Yield 65%). The molecularweight of Compound I thus obtained was measured using FAB-MS, and avalue of 551 (C₄₀H₂₅NO₂) was obtained. In addition, ¹H NMR (CDCl₃, 300MHz) of Compound I was measured, and the chemical shift values expectedfrom the structure of Compound I were obtained. Thus, the synthesis ofCompound I was secured. In addition, the glass transition temperature ofCompound I was measured using a differential scanning calorimetry, DSC7020 of Hitachi Hightech Co., and a value of Tg: 100° C. was obtained.

(Manufacture of Organic Electroluminescent Device)

An organic electroluminescent device was manufactured by the followingmethod. First, on an ITO-glass substrate patterned and washed inadvance, surface treatment using UV-ozone (O₃) was conducted. The layerthickness of an ITO layer (the first electrode) was about 150 nm. Afterozone treatment, the substrate was washed. After finishing washing, thesubstrate was set in a glass bell jar type evaporator for forming anorganic layer, and a hole injection layer, a HTL (a hole transportlayer), an emission layer and an electron transport layer wereevaporated one by one in a vacuum degree of about 10⁻⁴ to about 10⁻⁵ Pa.The material of the hole injection layer was 2-TNATA, and the thicknessthereof was about 60 nm. The materials of the HTL are shown in Table 1,below, and the thickness thereof was about 30 nm.

In addition, the thickness of the emission layer was about 25 nm. Thehost of the emission material was 9,10-di(2-naphthyl)anthracene (ADN). Adopant was 2,5,8,11-tetra-t-butylperylene (TBP). The doped amount of thedopant was about 3 wt % on the basis of the weight of the host. Thematerial of the electron transport layer was Alq₃, and the thicknessthereof was about 25 nm. Subsequently, the substrate was transferred toa glass bell jar type evaporator for forming a metal layer, and theelectron injection layer and a cathode material were evaporated in avacuum degree of about 10⁻⁴ to about 10⁻⁵ Pa. The material of theelectron injection layer was LiF, and the thickness thereof was about1.0 nm. The material of the second electrode was Al, and the thicknessthereof was about 100 nm.

TABLE 1 Example Current Life of device density Voltage LT50 manufactureHTL (mA/cm²) (V) (hr) Example 1 Compound C 10 6.3 2,000 Example 2Compound E 10 6.5 1,800 Example 3 Compound G 10 6.6 2,200 Example 4Compound I 10 6.6 2,100 Comparative Comparative 10 6.6 1,100 Example 1Compound C1 Comparative Comparative 10 8.2 1,300 Example 2 Compound C2Comparative Comparative 10 7.6 1,300 Example 3 Compound C3

In Table 1, Comparative Compounds C1, C2, and C3 are illustrated below.

(Evaluation of Properties)

Then, the driving voltage and the emission life of the organicelectroluminescent devices were measured. In addition, theelectroluminescent properties of the organic EL device 100 thusmanufactured were evaluated using C9920-11 brightness light distributioncharacteristics measurement system of HAMAMATSU Photonics Co. Inaddition, current density was measured at 10 mA/cm², and half-life wasmeasured at 1,000 cd/m². The results are shown in Table 1.

According to Table 1, the life was improved for Examples 1 to 4 whencompared to that of Comparative Examples 1 to 3. Particularly, the lifewas more improved for Examples 1, 3 and 4 when compared to that ofComparative Example 3. It would be found that a structure including anaryl group in which three phenyl groups were combined and condensedexhibited improved effects of the life. When comparing Examples 1 and 2,all properties of Example 1 were better than those of Example 2. Inaddition, When comparing Example 3 and Comparative Example 1, theemission life of Example 3 was improved greatly than ComparativeExample 1. Thus, it would be preferable that all dibenzofuranyl groupswere combined with a nitrogen atom at position 3. In exemplaryembodiments, the emission life of the organic electroluminescent devicewas largely improved specifically in a blue region. In addition, since acompound group according to exemplary embodiments has a wide energy gapwhich may correspond to a blue region, application from a green regionto a red region may be possible.

By way of summation and review, in an organic electroluminescent device,holes and electrons injected from the anode and the cathode mayrecombine in the emission layer to generate excitons, and light may beemitted via the transition of the excitons to a ground state. As a holetransport material used in the hole transport layer, e.g., a monoaminecompound including a dibenzofuranyl group may be used.

An organic electroluminescent device including some monoamine compoundsas a hole transport material may not provide satisfactory valuesconcerning emission life. For example, a monoamine compound derivativemay not provide satisfactory values of the emission life of the organicelectroluminescent device.

The embodiments may provide a material for an organic electroluminescentdevice which may help improve the emission life of an organicelectroluminescent device.

According to an embodiment, the emission life of the organicelectroluminescent device may be improved.

As described above, the material for an organic electroluminescentdevice according to an embodiment may have the configuration of Formula1, and the emission life of the organic electroluminescent device usingthe same may be largely improved. Thus, the material for an organicelectroluminescent device according to exemplary embodiments may bepractically used in various areas.

Example embodiments have been disclosed herein, and although specificterms are employed, they are used and are to be interpreted in a genericand descriptive sense only and not for purpose of limitation. In someinstances, as would be apparent to one of ordinary skill in the art asof the filing of the present application, features, characteristics,and/or elements described in connection with a particular embodiment maybe used singly or in combination with features, characteristics, and/orelements described in connection with other embodiments unless otherwisespecifically indicated. Accordingly, it will be understood by those ofskill in the art that various changes in form and details may be madewithout departing from the spirit and scope of the present invention asset forth in the following claims.

What is claimed is:
 1. A material for an organic electroluminescentdevice, the material comprising a monoamine compound represented by thefollowing Formula 1:

wherein, in Formula 1, R₁ and R₂ are each independently a hydrogen atom,a halogen atom, an alkyl group having 1 to 15 carbon atoms, asubstituted or unsubstituted aryl group having 6 to 30 ring carbonatoms, or a substituted or unsubstituted heteroaryl group having 1 to 30ring carbon atoms, and Ar₁ is a moiety represented by the followingFormula 2,—(Ar₂)₁—(Ar₃)_(m)—Ar₄   [Formula 2] wherein, in Formula 2, Ar₂, Ar₃, andAr₄ are each independently a substituted or unsubstituted aryl grouphaving 6 to 50 ring carbon atoms, and l+m is an integer from 0 to
 2. 2.The material for an organic electroluminescent device as claimed inclaim 1, wherein Ar₁ includes three combined or condensed substituted orunsubstituted phenyl groups.
 3. The material for an organicelectroluminescent device as claimed in claim 2, wherein Ar₁ includes asubstituted or unsubstituted phenanthrenyl group.
 4. The material for anorganic electroluminescent device as claimed in claim 2, wherein Ar₁includes a substituted or unsubstituted p-terphenyl group.
 5. Thematerial for an organic electroluminescent device as claimed in claim 2,wherein Ar₁ includes a substituted or unsubstituted naphthalenylphenylgroup.
 6. The material for an organic electroluminescent device asclaimed in claim 1, wherein all dibenzofuranyl groups that are directlybonded with a nitrogen atom of the monoamine are bound to the nitrogenatom at a 3 position of the dibenzofuranyl group.
 7. The material for anorganic electroluminescent device as claimed in claim 1, wherein thecompound represented by Formula 1 includes one of the followingcompounds:


8. An organic electroluminescent device comprising a material for anorganic electroluminescent device, wherein the material for an organicelectroluminescent device includes a monoamine compound represented bythe following Formula 1:

wherein, in Formula 1, R₁ and R₂ are each independently a hydrogen atom,a halogen atom, an alkyl group having 1 to 15 carbon atoms, asubstituted or unsubstituted aryl group having 6 to 30 ring carbonatoms, or a substituted or unsubstituted heteroaryl group having 1 to 30ring carbon atoms, and Ar₁ is represented by the following Formula 2,—(Ar₂)₁—(Ar₃)_(m)—Ar₄   [Formula 2] wherein, in Formula 2, Ar₂, Ar₃, andAr₄ are each independently a substituted or unsubstituted aryl grouphaving 6 to 50 ring carbon atoms, and l+m is an integer from 0 to
 2. 9.The organic electroluminescent device as claimed in claim 8, wherein thematerial for an organic electroluminescent device is included in a holetransport layer.
 10. The organic electroluminescent device as claimed inclaim 8, wherein the compound represented by Formula 1 includes one ofthe following compounds: